docs: def update_html_symlink(html_dir):
      """"Maintail symlink: "today.html", "yesterday.html" """
      today = datetime.date.today()
      yesterday = datetime.date.today() - datetime.timedelta(days=1)
  
      for from_date, alias_name in (
              (today, 'today.html'), (yesterday, 'yesterday.html')):
          from_date_file_path = os.path.join(html_dir, 'day_%s.html' % from_date)
          symlink_path = os.path.join(html_dir, alias_name)
          try:                                                                                         
              os.unlink(symlink_path)                                                                  
          except OSError:                                                                              
              pass                                                                                     
          os.symlink(from_date_file_path, symlink_path)